My apologies if this is just rampant ignorance talking (including ignorance of American future obligations), but it appears to me that "The US has future obligations so large that even a magical 100% tax in a magically healthy economy cannot pay for them" is, as they say, an extraordinary claim requiring extraordinary evidence. Or at least some evidence.

And even were that proven (or at least were that to be slightly persuasive), there's still substantial arguing yet to be done, to argue that a refusal to raise taxes at all is an action in _favour_ of coping with debt (indeed, allegedly the only such action).